This invention relates to heatproof substances, particularly to a novel corrugated heatproof roofing.
Conventionally, there have existed corrugated roofings, such as plastic corrugated board, corrugated asbestos roofing etc. Among them, corrugated asbestos roofing is a major roofing used for heat-resisting, weather resisting purposes.
However, both corrugated asbestos roofing and other plastic corrugated boards reinforced with fibrous materials, such as, rags, glass fibers or asbestos merely offer a temporary heat resisting effect. After subjected to the sun light for a period, the temperature in the indoor space will be increased.
Generally, these roofings are made of low heat conducting materials which have poor heat-reflecting characteristics. The major component, asbestos, in the corrugated asbestos roofing has a low thermal conductivity of about 0.087 Btu/(hr)(ft) (F). Its thermal absorptivity is high, generally up to 0.96. It absorbs the radiating heat emitted from the sun and therefore the temperature thereof gradually increases. When the heat input and heat output of the roofing are in equilibrium, the temperature thereof become constant. At that time, the roofing has already emitted its absorbed heat into the indoor space. When the sunlight disappears, the absorbed heat of the roofing may still be transferred to the indoor space. Therefore, the temperature in the indoor space still remains high.
The inventor found that, to improve the heat resisting effect of corrugated asbestos roofing, it is necessary (a) to make multilayer roofing, (b) to reduce the heat absorptivity of the roofing and (c) to increase the reflectivity of the roofing.